Question

某班七個興趣小組人數(shù)分別為4，4，5，x，6，6，7．已知這組數(shù)據(jù)的平均數(shù)是5，則這組數(shù)據(jù)的中位數(shù)是（　�。�                                                                            

A．7                            B．6                            C．5                            D．4

Answer 1

C【考點】中位數(shù)；算術平均數(shù)．                                                            

【分析】本題可先算出x的值，再把數(shù)據(jù)按從小到大的順序排列，找出最中間的數(shù)，即為中位數(shù)．                 

【解答】解：∵某班七個興趣小組人數(shù)分別為4，4，5，x，6，6，7．已知這組數(shù)據(jù)的平均數(shù)是5，               

∴x=5×7﹣4﹣4﹣5﹣6﹣6﹣7=3，                                                            

∴這一組數(shù)從小到大排列為：3，4，4，5，6，6，7，                                    

∴這組數(shù)據(jù)的中位數(shù)是：5．                                                                   

故選C．                                                                                            

【點評】本題考查的是中位數(shù)，熟知中位數(shù)的定義是解答此題的關鍵．